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[Kelly]

Key Items for a YAN adjustable height drive terminal rear leg area.

1. Rear leg lift cylinder – return side, just to the left of the number you can see a grey area at the outside edge of ram, this is the hydraulic fitting for the "return" side of the lifting ram. The hoses for this ram are either carried on the snowcat destined to lift this terminal, lost in the lift maintenance shop or on the new company wood splitter.

2. Rear leg lift cylinder – lift or pressure side, again the fitting is just visible on the far edge. This cylinder is 1 of 3 that are used to adjust the terminal height. This ram uses hydraulic fluid from a cat hydraulic system to lift the terminal. With American sized threads it can be a bit of a problem to plumb as most snow cats of newer manufacture now have metric fittings. If this ram looks small in comparison to the rest of the terminal, it is! Lifts that have the motor room in the rear portion of its carriage travel are difficult to lift with this size ram. This problem is often over come by temporarily detensioning the lift (see #5 tension cylinder) and/or lifting the front leg rams.

3. Rear lower pivot for the tension cylinder – located just to the right and slightly below the number. This pin is often overlooked for "capture" devices in the case that its side plates might spread and cause the pin to slide out of its intended pivot position. This pin does hold the lift tension in this style of counterweight to carriage connection.

4. Counterweight rope attachment eye – An eye of this smaller diameter can only be used one time due to the deformation of the rope. Shortening of the rope is ok; if lengthening of the counterweight rope due to carriage adjustment is necessary a new rope will be needed. This system has been adapted from a chain style connection to the ram as it was found that the frequency of code mandated nondestructive testing of the chain was too costly and time consuming to perform.

5. Tension ram or cylinder – This tension device takes the place of a normal counterweight system in providing energy (in this case compressed nitrogen) to tension the lift. The upper part of the ram is stationary and the lower part (piston and rod) moves. Notice the large amount of gusseting steel above the ram to counter the force need to tension the lift.

5p. Pressure side of the tension ram - Compressed gas provides the force to this system and is stored in a box - see item #7. This gas is regulated to provide the proper force on the piston in the tension ram. Nitrogen is normally used due to its ability to displace moisture. This system has a pressure valve that will only release pressure slowly if the gas lines are damaged, preventing any sudden decrease in tension.

5R. Return side of tension ram - this side is inactive and not used unless a change in the counterweight rope is needed. Any pressure on this side of the piston indicates a leak in the piston seal.

6. Paint in this area looks damaged but is actually is the result of being applied over a foundation waterproofing sealant.

7. Storage box for gas bottles, pressure gauges, and safety hi/lo cutoffs. The bottom of the box is at winter time loading ramp height. This box is attached to the tension frame (see fig. #11) and moves vertically with the terminal.

8-8A. This is the tension frame and it wraps around the oval rear leg (see fig #12).

9. Incoming power and communication cables. These are routed though the rear leg to the motor room. These are inappropriately "tie-wrapped" to the counterweight ropes without any standoffs and will chafe from operational vibration.

10. Power meter. I have always wondered why you would attach a meter base at this height considering the lift is made to have over 10' of vertical travel. Come to think about it the meter on my house is 5' from the ground.

11. The tension frame applies the force to the oval tube (see fig #12) through these wheels (top one not shown). The subframe, wheels, bushings and its axels are often overlooked in inspections and nondestructive testing of the counterweight system.

12. Rear leg. This component is made of 2 tower tubes with flat plates welded to them. Conduit for the utilities is run to the top and the leg is also filled with concrete for strength.

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[liftmech]

We used to have a system like that (triple E-lift) but it was used for things like Busch and Heineken in 1998.
Murray-Latta had a very similar height-adjustment system, except it was powered by a hand pump mounted on a platform at crossarm level. Want to get warm in a hurry? Go raise or lower tower 1 or 6 on Baker's Chair 3 (1968). Come to think of it, M-L sold their patents to Yan in the late 70s/early 80s sometime. Was the chain fall Yan's only method of raising a terminal until then, or did they develop the hydraulic method before they got it from M-L?